package com.example.demo.niuke;

/**
 * @Description:
 * @Author: LLL
 * @Date: 2020-03-17 22:33
 **/

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashSet;

public class Main6 {
    //    public static void main(String[] args) throws IOException {
    ////        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    ////        String s = br.readLine();
    ////        ArrayList<Integer> list = new ArrayList<>();
    ////        int count = 0;
    ////        for (int i = s.length() - 1; i >= 0; i--) {
    ////            int c = s.charAt(i);
    ////            if (c >= 0 && c <= 127)
    ////                count++;
    ////        }
    ////        System.out.println(count);
    ////
    ////    }
    //    public static void main(String[] args) throws IOException {
    //        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    //        String str = br.readLine();
    //        //String[] Str = str.split("");
    //        char[] ch = new char[str.length()];
    //        HashSet<Character> set = new HashSet<Character>();
    //        for (int i = 0; i < str.length(); i++) {
    //            ch[i] = str.charAt(i);
    //            set.add(ch[i]);
    //        }
    //        System.out.println(set.size());
    //    }
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String s = br.readLine();
        HashSet<Integer> set = new HashSet<>();
        for (int i = s.length() - 1; i >= 0; i--) {
            int c = s.charAt(i);
            if (c > 0 && c < 127)
                set.add(c);
        }
        System.out.println(set.size());

    }
}